We will continue to study the relation between exposure conditions during rearing and visual discrimination capacities. In addition to attempting to clarify those aspects of two-dimensional shape which are dependent upon movement-produced feedback, we intend to investigate the development of responses to three-dimensional objects. In particular, we will explore the role of motor-visual feedback in acquisition of shape and size constancy. The role of eye and head movement in acquisition of visual-motor coordinations will be investigated. Eye movements will be prevented by section of cranial nerves III, IV and VI in kittens that have no prior exposure in light. The head will be immobilized by fusion of appropriate sections of spinal column. In humans, adult strabismics will be used to continue studies of the influence of motor outflow which controls eye orientation upon localization of targets in visual space. Work will continue on the loss and reacquisition of visual-motor capacities following lesion of cortical and sub-cortical areas in the brain of the kitten. We will also employ the techniques used in the visual discrimination studies to describe more precisely the abilities which survive various brain lesions and which are reacquired post-operatively.